1. Field of the Invention
This invention relates to a generally thin-walled, blow-molded plastic bottles, and more particularly to such bottles typically surrounded by a bottomless and topless supporting jacket of either polyethylene (PE), polypropylene (PP) or polyethylene terephthalate (PET) with a very thin overall wall thickness of 0.1 to 0.3 mm
2. Discussion of Related Art
Known processes for the production of plastic bottles in blow molds, so-called bottle blowing processes, are also suitable for the production of extremely thin-walled plastic bottles. Plastic bottles of polyethylene terephthalate (PET) are produced, for example, by initially injection-molding a parison and then blow-molding the parison under the effect of heat into the required bottle shape. Plastic bottles of polyethylene (PE) are produced, for example, by feeding a PE tube to the blow molds of bottle blowing machines and blow-molding the tube in the blow molds to form bottles. It is known that very thin-walled plastic bottles can be produced by these bottle blowing processes. These plastic bottles have a smooth surface texture. To increase the strength and stability of the bottles and to prevent them from bulging, particularly during and after filling with liquid, it is known (cf. EP-A-0 198 587) that the bottles can be provided with pronounced stabilizing and stiffening ribs and recesses. This requires particularly expensive and relatively complicated blow molds. The need for a uniform and constant wall thickness over the entire extent of the bottle wall is a problem which has not been satisfactorily solved in these known bottles.
Very thin-walled blow-molded plastic bottles of polyethylene (PE) with a wall thickness of 0.1 to 0.3 mm and a rectangular cross-section surrounded by a bottomless and topless supporting jacket of cardboard are known from DE-A-39 21 258 and have been on the market for some time. The need for a uniform and constant wall thickness over the entire extent of the bottle wall is again a problem which has not been satisfactorily solved in these bottles either. During blow molding in the blow molds, extremely thin zones well below the required wall thickness are formed in the 0.1 to 0.3 mm thick bottle wall; in some cases, holes are even formed in the bottle wall. Another disadvantage of these thin-walled plastic bottles is that the side walls show signs of buckling on removal from the blow mold and bulge out when filled with liquid or free-flowing product.
In addition, it is generally known that plastic bottles with standard wall thicknesses of 0.35 to 0.8 mm can be produced in blow molds toughened, for example, by etching or sandblasting if parts of the outer surface of the bottle are to have a matt or rough texture for reasons of optical design. However, this does not affect the stability or rigidity of the bottles on account of the relatively thick walls of the bottles to which this process has hitherto been applied.